Flame-retardant vanillin-derived monomers

ABSTRACT

A flame-retardant vanillin-derived monomer, a process for forming a flame-retardant polymer, and an article of manufacture comprising a material that contains flame-retardant vanillin-derived monomer are disclosed. The flame-retardant vanillin-derived monomer can be synthesized from vanillin obtained from a bio-based source, and can have at least one phosphoryl or phosphonyl moiety with phenyl, allyl, epoxide, or propylene carbonate substituents. The process for forming the flame-retardant polymer can include reacting a vanillin derivative and a flame-retardant phosphorus-based molecule to form the flame-retardant vanillin-derived monomer, and then polymerizing the flame-retardant vanillin-derived monomer. The material in the article of manufacture can be flame-retardant, and contain the flame-retardant vanillin-derived monomer. Examples of materials that can be in the article of manufacture can include resins, plastics, adhesives, polymers, etc.

BACKGROUND

The present disclosure relates to bio-renewable flame-retardantcompounds and, more specifically, flame-retardant vanillin-derivedmonomers.

Bio-based compounds provide a source of renewable materials for variousindustrial applications, such as polymers, flame retardants,cross-linkers, etc. One example of a bio-based compound that can be usedin these applications is vanillin (4-hydroxy-3-methoxybenzaldehyde).Vanillin is a plant metabolite and the main component of natural vanillaextract. While vanillin can be obtained from vanilla extract, orsynthesized from petroleum-based raw materials, a number ofbiotechnology processes are also used to produce vanillin. Theseprocesses can be plant-based or microorganism-based, and provide arenewable source of vanillin on an industrial scale.

SUMMARY

Various embodiments are directed to flame-retardant vanillin-derivedmonomers. The flame-retardant vanillin-derived monomers can have atleast one phosphoryl or phosphonyl moiety. Each phosphoryl or phosphonylmoiety can have at least one substituent selected from a groupconsisting of a phenyl substituent, an allyl substituent, an epoxidesubstituent, and a propylene carbonate substituent. The flame-retardantvanillin-derived monomers can be synthesized from vanillin obtained froma bio-based source. Additional embodiments are directed to forming aflame-retardant polymer. The polymer can be produced by forming avanillin derivative, forming a phosphorus-based flame-retardantmolecule, and reacting the vanillin derivative and the phosphorus-basedflame-retardant molecule with one another to form a flame-retardantvanillin-derived monomer. The flame-retardant vanillin-derived monomercan then be polymerized, forming the flame-retardant polymer. Thevanillin derivative can be a flame-retardant phenol vanillin derivative,a flame-retardant carboxylic acid vanillin derivative, a flame-retardantbenzyl alcohol vanillin derivative, a phenol diol vanillin derivative, acarboxylic acid diol derivative, a benzyl alcohol diol vanillinderivative. The phosphorus-based flame-retardant molecule can be aphosphate-based molecule or a phosphonate-based molecule with at leastone phenyl substituent, allyl substituent, epoxide substituent, orpropylene carbonate substituent. Further embodiments are directed to anarticle of manufacture comprising a material that contains theflame-retardant vanillin-derived monomer. The material can be a resin,plastic, adhesive, polymer, etc. The article of manufacture can alsocomprise a printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram illustrating a process of forming aflame-retardant polymer from flame-retardant vanillin-derived monomers,according to embodiments of the present disclosure.

FIG. 2A is a chemical reaction diagram illustrating processes ofsynthesizing three diol vanillin derivatives, according to embodimentsof the present disclosure.

FIG. 2B is a chemical reaction diagram illustrating processes ofsynthesizing three flame-retardant vanillin derivatives, according toembodiments of the present disclosure.

FIG. 3 is a diagrammatic representation of the molecular structures ofgeneric phosphorus-based flame-retardant molecules, according toembodiments of the present disclosure.

FIG. 4A is a chemical reaction diagram illustrating two processes ofsynthesizing the phosphate-based flame-retardant molecule, according toembodiments of the present disclosure.

FIG. 4B is a chemical reaction diagram illustrating two processes ofsynthesizing the phosphonate-based flame-retardant molecule, accordingto embodiments of the present disclosure.

FIG. 5A is a chemical reaction diagram illustrating a process ofsynthesizing a bis-functionalized flame-retardant phenolvanillin-derived monomer, according to some embodiments of the presentdisclosure.

FIG. 5B is a chemical reaction diagram illustrating a process ofsynthesizing a bis-propylene-carbonate-functionalized flame-retardantphenol vanillin-derived monomer, according to some embodiments of thepresent disclosure.

FIG. 5C is a chemical reaction diagram illustrating a process ofsynthesizing a mono-epoxide-functionalized flame-retardant phenolvanillin-derived monomer, according to some embodiments of the presentdisclosure.

FIG. 5D is a chemical reaction diagram illustrating a process ofsynthesizing a mono-propylene-carbonate-functionalized flame-retardantphenol vanillin-derived monomer, according to some embodiments of thepresent disclosure.

FIG. 5E is a chemical reaction diagram illustrating a process ofsynthesizing a bis-functionalized flame-retardant carboxylic acidvanillin-derived monomer, according to some embodiments of the presentdisclosure.

FIG. 5F is a chemical reaction diagram illustrating a process 500-6 ofsynthesizing a bis-propylene-carbonate-functionalized flame-retardantcarboxylic acid vanillin-derived monomer 530, according to someembodiments of the present disclosure.

FIG. 5G is a chemical reaction diagram illustrating a process ofsynthesizing a mono-epoxide-functionalized flame-retardant carboxylicacid vanillin-derived monomer, according to some embodiments of thepresent disclosure.

FIG. 5H is a chemical reaction diagram illustrating a process ofsynthesizing a mono-propylene-carbonate-functionalized flame-retardantcarboxylic acid vanillin-derived monomer, according to some embodimentsof the present disclosure.

FIG. 5I is a chemical reaction diagram illustrating a process ofsynthesizing a bis-functionalized flame-retardant benzyl alcoholvanillin-derived monomer, according to some embodiments of the presentdisclosure.

FIG. 5J is a chemical reaction diagram illustrating a process ofsynthesizing a bis-propylene-carbonate-functionalized flame-retardantbenzyl alcohol vanillin-derived monomer, according to some embodimentsof the present disclosure.

FIG. 5K is a chemical reaction diagram illustrating a process ofsynthesizing a mono-epoxide-functionalized flame-retardant benzylalcohol vanillin-derived monomer, according to some embodiments of thepresent disclosure.

FIG. 5L is a chemical reaction diagram illustrating a process ofsynthesizing a mono-propylene-carbonate-functionalized flame-retardantbenzyl alcohol vanillin-derived monomer, according to some embodimentsof the present disclosure.

FIG. 6A is a chemical reaction diagram illustrating a process of formingflame-retardant vanillin-based polymers derived from thebis-allyl-functionalized vanillin-derived monomers, according to someembodiments of the present disclosure.

FIG. 6B is a chemical reaction diagram illustrating a process of formingflame-retardant vanillin-based polymers derived from thebis-epoxide-functionalized vanillin-derived monomers, according to someembodiments of the present disclosure.

FIG. 6C is a chemical reaction diagram illustrating a process of formingflame-retardant vanillin-based polymers derived from thebis-propylene-carbonate-functionalized vanillin-derived monomers,according to some embodiments of the present disclosure.

FIG. 6D is a chemical reaction diagram illustrating a process of formingflame-retardant vanillin-based polymers derived from themono-propylene-carbonate-functionalized vanillin-derived monomers,according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

Bio-based compounds are increasingly being used in the synthesis ofsubstances that previously required petroleum-based raw materials. Onebenefit of bio-based compounds is that they are from renewableresources. Therefore, these compounds have applications in sustainable,or “green,” materials. Sustainable materials are becoming more and moreprevalent, due to the rising costs of fossil fuels and increasingenvironmental regulatory controls. Advances in biotechnology haveprovided numerous strategies for efficiently and inexpensively producingbio-based compounds on an industrial scale. Examples of these strategiescan include plant-based or microorganism-based approaches. Plant-basedapproaches can involve obtaining a material directly from a plant, orgrowing plant tissues or cells that can produce bio-based compounds fromvarious substrates using their own biosynthetic pathways.Microorganism-based approaches involve using native or geneticallymodified fungi, yeast, or bacteria to produce a desired compound from astructurally similar substrate.

Examples of substances that can be produced from bio-based compounds caninclude polymers, flame retardants, cross-linkers, etc. In someexamples, bio-based polymers and petroleum-based polymers are blended toform a polymer composite. However, polymers can also be entirelybio-based, or produced from a combination of bio- and petroleum-basedmonomers. Bio-based compounds can also impart flame-retardant propertiesto bio- and petroleum-based polymers. For example, flame-retardantmonomers or cross-linkers can be incorporated into polymers.Additionally, flame-retardant molecules can be blended or chemicallyreacted with the polymers.

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is one example of a bio-basedcompound that has applications as a component of various polymers,resins, and small molecules. Vanillin is a plant metabolite and the maincomponent of natural vanilla extract. It can be obtained from the plant-and microorganism-based bio-sources discussed above, or synthesized frompetroleum-based raw materials. According to some embodiments of thepresent disclosure, vanillin is used as a precursor for flame-retardantmonomers. These vanillin-derived flame-retardant monomers polymerize toform flame-retardant polymers.

FIG. 1 is a flow diagram 100 illustrating a process of forming aflame-retardant polymer from flame-retardant vanillin-derived monomers108, according to embodiments of the present disclosure. Thevanillin-derived monomers 108 can be bis-functionalized ormono-functionalized. The mono-functionalized flame-retardantvanillin-derived monomers have one functional group that participates inthe polymerization, while the bis-functionalized monomers have twofunctional groups that participate in the polymerization. Process 100begins with the formation of a phosphorus-based flame-retardantmolecule. This is illustrated at step 105. The phosphorus-basedflame-retardant molecule has either a phosphoryl or phosphonyl moiety(collectively referred to as an FR group) with an attached R group.Examples of R groups that can be attached to the FR group can includephenyl substituents, epoxide substituents, allyl substituents, andpropylene carbonate substituents. The phenyl substituents do notparticipate in the polymerization reactions. The syntheses andstructures of phosphorus-based flame-retardant molecules are discussedin greater detail with regard to FIGS. 3, and 4A-4D.

Process 100 continues with the formation of a vanillin derivative. Thisis illustrated at step 110. The vanillin derivative is either a diolvanillin derivative with two hydroxyl groups or a flame-retardantvanillin derivative that has one flame-retardant group and one hydroxylgroup. The diol vanillin derivatives are formed in a reaction thatreplaces vanillin's aldehyde group with a hydroxyl. The flame-retardantvanillin derivatives are formed by a reaction of vanillin with thephosphorus-based flame-retardant molecule and a reaction that replacesvanillin's aldehyde functional group with a hydroxyl group. Examples ofreactions that can convert the aldehyde group to a hydroxyl group caninclude oxidation by sodium percarbonate, oxidation by potassiumpermanganate, and reduction by sodium borohydride.

The structures and syntheses of the diol vanillin derivatives arediscussed in greater detail with regard to FIG. 2A, and the structuresand syntheses of the flame-retardant vanillin derivatives are discussedin greater detail with regard to FIG. 2B. It should be noted that theformation of the vanillin derivative at step 110 is illustrated asoccurring after the formation of the phosphorus-based flame-retardantmolecule at step 105. However, in some embodiments, step 110 can occurbefore step 105.

The vanillin derivative and the phosphorus-based flame-retardantmolecule are chemically reacted in order to form a flame-retardantvanillin-derived monomer 108. This is illustrated at step 115. Theidentity of the M group on the flame-retardant vanillin-derived monomer108 is determined by the phosphorus-based flame-retardant molecule andthe vanillin derivative used in the reaction. The phosphorus-basedflame-retardant molecules react with hydroxyl groups on the vanillinderivatives synthesized in step 105 to provide the FR group with theattached R group. Examples of FR groups, as well as the syntheses andstructures of flame-retardant vanillin-derived monomers 108 arediscussed in greater detail with regard to FIGS. 5A-5L.

The flame-retardant vanillin-derived monomer 108 is polymerized under avariety of reaction conditions. This is illustrated at step 120. Thereaction conditions under which the polymerization occurs are discussedin greater detail with regard to FIGS. 6A-6D. The polymerization of theflame-retardant vanillin-derived monomers 108 forms a variety offlame-retardant polymers that have a number of applications, as isdiscussed in greater detail below.

FIG. 2A is a chemical reaction diagram illustrating processes 200-1,200-2, and 200-3 of synthesizing three diol vanillin derivatives,according to embodiments of the present disclosure. The three diolvanillin derivatives are a phenol diol derivative 210, a carboxylic aciddiol derivative 220, and a benzyl alcohol diol derivative 230. Thesevanillin derivatives are precursors for the bis-functionalizedflame-retardant vanillin-derived monomers 108. The syntheses of thebis-functionalized flame-retardant vanillin-derived monomers 108 fromthe diol vanillin derivatives are described in greater detail withregard to FIGS. 5A, 5B, 5E, 5F, 5I, and 5J.

In process 200-1, the phenol diol derivative 210 of vanillin is producedin an oxidation reaction with sodium percarbonate. Deionized water isadded to a solution of vanillin 205 in tetrahydrofuran (THF). Theresulting vanillin/THF/H₂O solution is degassed with an inert gas (e.g.,argon or nitrogen). While agitating the mixture, sodium percarbonate(Na₂CO₃.1.5H₂O₂) is added until pH=3 is reached, thus quenching thereaction. After quenching the reaction, the THF is evaporated, and theaqueous phase is extracted with ethyl acetate. The organic phases arecollected, washed with brine, and dried over anhydrous sodium sulfate(Na₂SO₄). The ethyl acetate is removed under reduced pressure, yieldingthe isolated phenol diol derivative 210.

In process 200-2, the carboxylic acid diol derivative 220 of vanillin isproduced in an oxidation reaction with potassium permanganate. Potassiumpermanganate (KMnO₄) is added to an acetone/H₂O solution of vanillin205. The mixture is stirred for approximately 1.5 hours at roomtemperature. Sodium bisulfite (NaHSO₃) in hydrochloric acid (HCl) isadded to the resulting purple mixture until the mixture is colorless.The mixture is extracted with ethyl acetate, and the organic phases arecollected, washed with brine, and dried over anhydrous magnesium sulfate(MgSO₄). The ethyl acetate is removed under reduced pressure, yieldingthe isolated carboxylic acid diol derivative 220.

In process 200-3, the benzyl alcohol diol derivative 230 of vanillin isproduced in a reduction reaction with sodium borohydride. Sodiumborohydride (NaBH₄) is added to a solution of vanillin 205 in anhydrousether or tetrahydrofuran (THF). The mixture is stirred at roomtemperature under an inert gas (e.g., argon or nitrogen) forapproximately four hours. The mixture is then concentrated, and purifiedby column chromatography to give the benzyl alcohol diol derivative 230as a colorless oil.

FIG. 2B is a chemical reaction diagram illustrating processes 200-4,200-5, and 200-6 of synthesizing three flame-retardant vanillinderivatives, according to embodiments of the present disclosure. Thethree flame-retardant vanillin derivatives are a phenol flame-retardantderivative 215, a carboxylic acid flame-retardant derivative 225, and abenzyl alcohol flame-retardant derivative 235. These vanillinderivatives are precursors for the mono-functionalized flame-retardantvanillin-derived monomers 108. The syntheses of the mono-functionalizedflame-retardant vanillin-derived monomers 108 are described in greaterdetail with regard to FIGS. 5C, 5D, 5G, 5H, 5K, and 5L.

In process 200-4, the phenol flame-retardant derivative 215 of vanillinis produced. The first step in this reaction replaces vanillin'shydroxyl group with an FR group. The FR group is provided by a reactionbetween vanillin 205 and either diphenyl chlorophosphate (DPCPa) ordiphenylphosphinic chloride (DPCPo), as well as catalyticdimethylaminopyridine (DMAP). In some embodiments, stoichiometrictriethylamine is used instead of DMAP. If the reaction is carried outwith DPCPa, the phenol flame-retardant derivative 215 will havephosphoryl FR groups, and, if the reaction is carried out with DPCPo,the phenol flame-retardant derivative 215 will have phosphonyl FRgroups.

In the second step in process 200-4, deionized water (H₂O) andtetrahydrofuran (THF) are added to the reaction. The resulting mixtureis degassed with an inert gas (e.g., argon or nitrogen). While agitatingthe mixture, sodium percarbonate (Na₂CO₃.1.5H₂O₂) is added until pH=3 isreached, thus quenching the reaction. After quenching the reaction, theTHF is evaporated, and the aqueous phase is extracted with ethylacetate. The organic phases are collected, washed with brine, and driedover anhydrous sodium sulfate (Na₂SO₄). The ethyl acetate is removedunder reduced pressure, yielding the isolated phenol derivative 215.

In process 200-5, the carboxylic acid flame-retardant derivative 225 ofvanillin is produced. The first step in this reaction replacesvanillin's hydroxyl group with an FR group, and is carried out undersubstantially the same conditions as the first step in process 200-4. Inthe second step, potassium permanganate (KMnO₄) in an acetone/H₂Osolution is added to the reaction. The mixture is stirred forapproximately 1.5 hours at room temperature. A solution of sodiumbisulfite (NaHSO₃) in hydrochloric acid (HCl) is added to the resultingpurple mixture until the mixture is colorless. The mixture is extractedwith ethyl acetate, and the organic phases are collected, washed withbrine, and dried over anhydrous magnesium sulfate (MgSO₄). The ethylacetate is removed under reduced pressure, yielding the isolatedcarboxylic acid flame-retardant derivative 225.

In process 200-6, the benzyl alcohol flame-retardant derivative 235 isproduced. The first step in this reaction replaces vanillin's hydroxylgroup with an FR group, and is carried out under substantially the sameconditions as the first step in process 200-4. In the second step,sodium borohydride (NaBH₄) is added to a solution of vanillin 205 inanhydrous ether or tetrahydrofuran (THF). The mixture is stirred at roomtemperature under an inert gas (e.g., argon or nitrogen) forapproximately four hours. The mixture is then concentrated, and purifiedby column chromatography to give the benzyl alcohol flame-retardantderivative 235.

FIG. 3 is a diagrammatic representation of the molecular structures 300of generic phosphorus-based flame-retardant molecules 340, according toembodiments of the present disclosure. Each phosphorus-basedflame-retardant molecule 340 is either a phosphate-based flame-retardantmolecule 340-1 or a phosphonate-based flame-retardant molecule 340-2.Herein, phosphoryl and phosphonyl moieties are replaced by theabbreviation “FR” in order to simplify illustrations of the molecularstructures. Each phosphorus-based flame-retardant molecule 340 has aphenyl (Ph) substituent and an R group.

The identities of the R groups bound to the flame-retardant molecules340 vary, and are discussed in greater detail with respect to FIGS. 4A,4B, 5B, 5D, 5F, 5H, 5J, and 5L. Additionally, in some embodiments, thephenyl group is replaced by another alkyl substituent (e.g., methyl,ethyl, propyl, isopropyl, etc.). The syntheses of the phosphorus-basedflame-retardant molecules 340 are discussed with regard to FIGS. 4A and4B. The phosphorus-based flame-retardant molecules 340 are reacted withthe vanillin derivatives 210, 215, 220, 225, 230, and 235 to formflame-retardant vanillin-derived monomers 108. These reactions arediscussed in greater detail with regard to FIGS. 5A, 5C, 5E, 5G, 5I, and5K.

FIG. 4A is a chemical reaction diagram illustrating two processes 400-1and 400-2 of synthesizing the phosphate-based flame-retardant molecule340-1, according to embodiments of the present disclosure. In bothprocesses 400-1 and 400-2, an alcohol 405 is a starting material for thephosphate-based flame-retardant molecule 340-1. The alcohol 405 haseither an allyl R group 407 or an epoxide R group 408. It should benoted that, though an allyl group 407 with a single methylene spacergroup is illustrated here, other alcohols with allylic chains of varyinglengths (e.g., one to twelve methylene spacer groups) could be used.Additionally, alcohols with acrylate substituents are used in someembodiments.

In process 400-1, the alcohol 405 is reacted with diphenyl phosphite andtitanium isopropoxide (Ti(O^(i)Pr)₄) in benzene to produce a precursor410 to the phosphate-based flame-retardant molecule 340-1. In thispseudo-transesterification reaction, the precursor 410 is formed when aphenyl (Ph) substituent on diphenyl phosphite is replaced by an allyl407 or epoxide 408 R group from the alcohol 405. The precursor 410 isthen reacted with thionyl chloride (SOCl₂) and carbon tetrachloride(CCl₄) over a range of 0° C. to room temperature (RT), forming thephosphate-based flame-retardant molecule 340-1 with an allyl 407 orepoxide 408 R group.

In process 400-2, the alcohol 405 is reacted with phenyldichlorophosphate in a tetrahydrofuran (THF) solution containingtriethyl amine (Et₃N). This process is carried out over a range of 0° C.to room temperature (RT). A chloride on the phenyl dichlorophosphate isreplaced by the allyl 407 or epoxide 408 R group from the alcohol 405,forming the phosphate-based flame-retardant molecule 340-1 with an allyl407 or epoxide 408 R group.

FIG. 4B is a chemical reaction diagram illustrating two processes 400-3and 400-4 of synthesizing the phosphonate-based flame-retardant molecule340-2, according to embodiments of the present disclosure. In bothprocesses 400-3 and 400-4, an organochloride 420 is a starting materialfor the phosphonate-based flame-retardant molecule 340-2. Theorganochloride has either an allyl R group 407 or an epoxide R group408. It should be noted that, as in the case of the alcohol 405, otherorganochlorides with allylic chains of varying lengths (e.g., one totwelve methylene spacer groups) could be used. Additionally,organochlorides with acrylate substituents are used in some embodiments.

In process 400-3, the organochloride 420 is reacted with triphenylphosphite (P(OPh)₃). The mixture is heated, either by refluxing intoluene or microwaving (mw) in ethanol (EtOH), producing a phosphonylester precursor 425 to the phosphonate-based flame-retardant molecule340-2. The phosphonyl ester precursor 425 is reacted with phosphoruspentachloride (PCl₅) to form the phosphonate-based flame-retardantmolecule 340-2 with an allyl 307 or epoxide 308 R group.

In process 400-4, a mixture of organochloride 420 and triphenylphosphite (P(OPh)₃) is heated, either by refluxing in toluene ormicrowaving (mw) in ethanol (EtOH), forming a phenylphosphinic acidprecursor 427 to the phosphonate-based flame-retardant molecule 340-2.The reaction is then quenched by raising the pH of the solution. In thisprophetic example, an ethanol (EtOH)/water (H₂O) solution of sodiumhydroxide (NaOH) is added to the reaction mixture. However, in someembodiments, bases other than sodium hydroxide, such as potassiumhydroxide or lithium hydroxide, are used to quench the reaction. Whenthe reaction has been quenched, thionyl chloride (SOCl₂) is added to thephenylphosphinic acid precursor 427, producing the phosphonate-basedflame-retardant molecule 340-2 with an allyl 307 or epoxide 308 R group.

FIG. 5A is a chemical reaction diagram illustrating a process 500-1 ofsynthesizing a bis-functionalized flame-retardant phenolvanillin-derived monomer 505, according to some embodiments of thepresent disclosure. In process 500-1, the phenol diol derivative 210 ofvanillin is reacted with a phosphorus-based flame-retardant molecule 340and catalytic dimethylaminopyridine (DMAP) in a dichloromethane (DCM)solution. In some embodiments, stoichiometric triethylamine is usedinstead of DMAP. Stirring this mixture yields the bis-functionalizedflame-retardant phenol vanillin-derived monomer 505.

If process 500-1 is carried out with a phosphorus-based flame-retardantmolecule 340 having an allyl R group 407, the bis-functionalizedflame-retardant phenol vanillin-derived monomer 505 will be abis-allyl-functionalized flame-retardant phenol vanillin-derived monomer505-1. Likewise, if process 500-1 is carried out with a phosphorus-basedflame-retardant molecule 340 having an epoxide R group 408, thebis-functionalized flame-retardant phenol vanillin-derived monomer 505will be a bis-epoxide-substituted flame-retardant phenolvanillin-derived monomer 505-2. If the process is carried out with thephosphate-based flame-retardant molecule 340-1, the bis-functionalizedflame-retardant phenol vanillin-derived monomer 505 will have aphosphoryl FR group, and, if the reaction is carried out with thephosphonate-based flame-retardant molecule 340-2, the bis-functionalizedflame-retardant phenol vanillin-derived monomer 505 will have aphosphonyl FR group.

FIG. 5B is a chemical reaction diagram illustrating a process 500-2 ofsynthesizing a bis-propylene-carbonate-functionalized flame-retardantphenol vanillin-derived monomer 510, according to some embodiments ofthe present disclosure. The bis-epoxide-functionalized flame-retardantphenol vanillin-derived monomer 505-2 of vanillin is combined withlithium bromide (LiBr). Carbon dioxide (CO₂) is added to the mixture,either by injecting into the headspace of the reaction flask, or bybubbling through the solution. This step yields thebis-propylene-carbonate-functionalized flame-retardant phenolvanillin-derived monomer 510.

FIG. 5C is a chemical reaction diagram illustrating a process 500-3 ofsynthesizing a mono-epoxide-functionalized flame-retardant phenolvanillin-derived monomer 515, according to some embodiments of thepresent disclosure. In process 500-3, the flame-retardant phenolderivative 215 is reacted with the phosphorus-based flame-retardantmolecule 340 having an epoxide R group 408 and catalyticdimethylaminopyridine (DMAP) in a dichloromethane (DCM) solution. Insome embodiments, stoichiometric triethylamine is used instead of DMAP.Stirring this mixture yields the mono-epoxide-functionalizedflame-retardant phenol vanillin-derived monomer 515.

FIG. 5D is a chemical reaction diagram illustrating a process 500-4 ofsynthesizing a mono-propylene-carbonate-functionalized flame-retardantphenol vanillin-derived monomer 520, according to some embodiments ofthe present disclosure. The mono-epoxide-functionalized flame-retardantphenol vanillin-derived monomer 515 is combined with lithium bromide(LiBr). Carbon dioxide (CO₂) is added to the mixture, either byinjecting into the headspace of the reaction flask, or by bubblingthrough the solution. This step yields themono-propylene-carbonate-functionalized flame-retardant phenolvanillin-derived monomer 520.

FIG. 5E is a chemical reaction diagram illustrating a process 500-5 ofsynthesizing a bis-functionalized flame-retardant carboxylic acidvanillin-derived monomer 525, according to some embodiments of thepresent disclosure. In process 500-5, the carboxylic acid diolvanillin-derived monomer 220 is reacted with a phosphorus-basedflame-retardant molecule 340 and catalytic dimethylaminopyridine (DMAP)in a dichloromethane (DCM) solution. In some embodiments, stoichiometrictriethylamine is used instead of DMAP. Stirring this mixture yields thebis-functionalized flame-retardant carboxylic acid vanillin-derivedmonomer 525.

If process 500-5 is carried out with a phosphorus-based flame-retardantmolecule 340 having an allyl R group 407, the bis-functionalizedflame-retardant carboxylic acid vanillin-derived monomer 525 will be abis-allyl-functionalized flame-retardant carboxylic acidvanillin-derived monomer 525-1. Likewise, if process 500-5 is carriedout with a phosphorus-based flame-retardant molecule 340 having anepoxide R group 408, the functionalized flame-retardant carboxylic acidvanillin-derived monomer 525 will be a bis-epoxide-functionalizedflame-retardant carboxylic acid vanillin-derived monomer 525-2. If theprocess is carried out with the phosphate-based flame-retardant molecule340-1, the bis-functionalized flame-retardant carboxylic acidvanillin-derived monomer 525 will have a phosphoryl FR group, and, ifthe reaction is carried out with the phosphonate-based flame-retardantmolecule 340-2, the functionalized flame-retardant carboxylic acidvanillin-derived monomer 525 will have a phosphonyl FR group.

FIG. 5F is a chemical reaction diagram illustrating a process 500-6 ofsynthesizing a bis-propylene-carbonate-functionalized flame-retardantcarboxylic acid vanillin-derived monomer 530, according to someembodiments of the present disclosure. The bis-epoxide-functionalizedflame-retardant carboxylic acid vanillin-derived monomer 525-2 iscombined with lithium bromide (LiBr). Carbon dioxide (CO₂) is added tothe mixture, either by injecting into the headspace of the reactionflask, or by bubbling through the solution. This step yields thebis-propylene-carbonate-functionalized flame-retardant carboxylic acidvanillin-derived monomer 530.

FIG. 5G is a chemical reaction diagram illustrating a process 500-7 ofsynthesizing a mono-epoxide-functionalized flame-retardant carboxylicacid vanillin-derived monomer 535, according to some embodiments of thepresent disclosure. In process 500-7, the flame-retardant carboxylicacid vanillin-derived monomer 225 is reacted with the phosphorus-basedflame-retardant molecule 340 having an epoxide R group 408 and catalyticdimethylaminopyridine (DMAP) in a dichloromethane (DCM) solution. Insome embodiments, stoichiometric triethylamine is used instead of DMAP.Stirring this mixture yields the mono-epoxide-functionalizedflame-retardant carboxylic acid vanillin-derived monomer 535.

FIG. 5H is a chemical reaction diagram illustrating a process 500-8 ofsynthesizing a mono-propylene-carbonate-functionalized flame-retardantcarboxylic acid vanillin-derived monomer 540, according to someembodiments of the present disclosure. The mono-epoxide-functionalizedflame-retardant carboxylic acid vanillin-derived monomer 535-2 iscombined with lithium bromide (LiBr). Carbon dioxide (CO₂) is added tothe mixture, either by injecting into the headspace of the reactionflask, or by bubbling through the solution. This step yields themono-propylene-carbonate-functionalized flame-retardant carboxylic acidvanillin-derived monomer 540.

FIG. 5I is a chemical reaction diagram illustrating a process 500-9 ofsynthesizing a bis-functionalized flame-retardant benzyl alcoholvanillin-derived monomer 545, according to some embodiments of thepresent disclosure. The benzyl alcohol diol derivative 230 of vanillinis reacted with a phosphorus-based flame-retardant molecule 340 andcatalytic dimethylaminopyridine (DMAP) in a dichloromethane (DCM)solution. In some embodiments, stoichiometric triethylamine is usedinstead of DMAP. Stirring this mixture yields the bis-functionalizedflame-retardant benzyl alcohol vanillin-derived monomer 545.

If process 500-9 is carried out with a phosphorus-based flame-retardantmolecule 340 having an allyl R group 407, the bis-functionalizedflame-retardant benzyl alcohol vanillin-derived monomer 545 will be abis-allyl-functionalized flame-retardant benzyl alcohol vanillin-derivedmonomer 545-1. Likewise, if process 500-9 is carried out with aphosphorus-based flame-retardant molecule 340 having an epoxide R group408, the bis-functionalized flame-retardant benzyl alcoholvanillin-derived monomer 545 will be a bis-epoxide-substitutedflame-retardant benzyl alcohol vanillin-derived monomer 545-2. If thereaction is carried out with the phosphate-based flame retardantmolecule 340-1, the bis-functionalized flame retardant benzyl alcoholvanillin-derived monomer 545 will have phosphoryl FR groups, and, if thereaction is carried out with the phosphonate-based flame-retardantmolecule 340-2, the bis-functionalized flame-retardant benzyl alcoholvanillin-derived monomer 545 will have phosphonyl FR groups.

FIG. 5J is a chemical reaction diagram illustrating a process 500-10 ofsynthesizing a bis-propylene-carbonate-functionalized flame-retardantbenzyl alcohol vanillin-derived monomer 550, according to someembodiments of the present disclosure. The bis-epoxide-functionalizedflame-retardant benzyl alcohol vanillin-derived monomer 545-2 iscombined with lithium bromide (LiBr). Carbon dioxide (CO₂) is added tothe mixture, either by injecting into the headspace of the reactionflask, or by bubbling through the solution. The reaction yields thebis-propylene-carbonate-functionalized flame-retardant benzyl alcoholvanillin-derived monomer 550.

FIG. 5K is a chemical reaction diagram illustrating a process 500-11 ofsynthesizing a mono-epoxide-functionalized flame-retardant benzylalcohol vanillin-derived monomer 555, according to some embodiments ofthe present disclosure. In process 500-11, the flame-retardant benzylalcohol derivative 235 is reacted with the phosphorus-basedflame-retardant molecule 340 having an epoxide R group 408 and catalyticdimethylaminopyridine (DMAP) in a dichloromethane (DCM) solution. Insome embodiments, stoichiometric triethylamine is used instead of DMAP.Stirring this mixture yields the mono-epoxide-functionalizedflame-retardant benzyl alcohol vanillin-derived monomer 555.

FIG. 5L is a chemical reaction diagram illustrating a process 500-12 ofsynthesizing a mono-propylene-carbonate-functionalized flame-retardantbenzyl alcohol vanillin-derived monomer 560, according to someembodiments of the present disclosure. The mono-epoxide-functionalizedflame-retardant benzyl alcohol vanillin-derived monomer 555-2 iscombined with lithium bromide (LiBr). Carbon dioxide (CO₂) is added tothe mixture, either by injecting into the headspace of the reactionflask, or by bubbling through the solution. This step yields themono-propylene-carbonate-functionalized flame-retardant benzyl alcoholvanillin-derived monomer 560.

In some embodiments, the processes of forming substitutedflame-retardant vanillin-derived monomers illustrated in FIGS. 5A, 5C,5E, 5G, 5I and 5K are carried out with a mixture of both thephosphate-based 340-1 and the phosphonate-based 340-2 flame retardantmolecules. Carrying out these reactions with a mixture of thephosphate-340-1 and phosphonate-based 340-2 flame retardant moleculescan result in substituted flame-retardant vanillin-derived monomers withboth phosphoryl and phosphonyl FR groups. However, in some instances,adding a mixture of phosphate-340-1 and phosphonate-based 340-2 flameretardant molecules can result in the production of functionalizedflame-retardant vanillin-derived monomers with all phosphoryl or allphosphonyl FR groups. Additionally, adding both phosphate-340-1 andphosphonate-based 340-2 flame retardant molecules to the reaction canyield a mixture of products that includes some combination ofderivatives with either all phosphoryl or all phosphonyl FR groups andderivatives with both phosphoryl and phosphonyl FR groups.

FIG. 6A is a chemical reaction diagram illustrating a process 600-1 offorming flame-retardant vanillin-based polymers 610 derived from thebis-allyl-functionalized vanillin-derived monomers 505-1, 525-1, and545-1, according to some embodiments of the present disclosure. Theallyl-functionalized vanillin derivative polymer 610 is shown having anoval 601 representing the vanillin moiety in the flame-retardantvanillin-derived monomer 108 in order to simplify the illustration ofthe molecule structure. The oval can be a phenol-derived moiety 602 fromeither the phenol diol vanillin derivative 210 or the phenolflame-retardant vanillin derivative 215, a carboxylic acid-derivedmoiety 603 from either the carboxylic acid diol vanillin derivative 220or the carboxylic acid flame-retardant vanillin derivative 225, or abenzyl alcohol-derived moiety 604 from either the benzyl alcohol diolvanillin derivative 230 or the benzyl alcohol flame-retardant vanillinderivative 235.

In process 600-1, the flame-retardant vanillin-based polymers 610derived from the bis-allyl-functionalized vanillin-derived monomers areformed by reacting a bis-allyl-functionalized vanillin-derived monomer505-1, 525-1, or 545-1 with a Ziegler-Natta catalyst. Ziegler-Nattacatalysts catalyze the polymerization of 1-alkenes. Examples of thesecatalysts can include heterogeneous Ziegler-Natta catalysts basedtitanium compounds and homogeneous Ziegler-Natta catalysts based oncomplexes of titanium, zirconium, or hafnium. Heterogeneous andhomogeneous Ziegler-Natta catalysts can be used in combination withorganoaluminum co-catalysts in some embodiments.

FIG. 6B is a chemical reaction diagram illustrating a process 600-2 offorming flame-retardant vanillin-based polymers 620 derived from thebis-epoxide-functionalized vanillin-derived monomers, 505-2, 525-2, and545-2, according to some embodiments of the present disclosure. Thebis-epoxide-functionalized vanillin-derived monomer 505-2, 525-2, or545-2 is reacted with a base and a compound with at least two hydroxyl(OH) groups or at least two amino (NH₂) groups (e.g., a diol, polyol,diamine, polyamine, etc.) 611. These compounds 611 are illustrated as agray oval with attached A groups. The A group represents a hydroxylgroup or an amino group. It should be noted that, while two A groups areillustrated, there can be more than two A groups in some embodiments.Additionally, in some embodiments, the bis-epoxide functionalizedvanillin-derived monomer 505-2, 525-2, or 545-2 self-polymerizes underbasic conditions. In these instances, the reaction does not include thecompound with at least two hydroxyl groups or at least two amino groups611.

FIG. 6C is a chemical reaction diagram illustrating a process 600-3 offorming flame-retardant vanillin-based polymers 630 derived from thebis-propylene-carbonate-functionalized vanillin-derived monomers 510,530, and 550, according to some embodiments of the present disclosure.In process 600-3, a bis-propylene-carbonate-functionalizedvanillin-derived monomer 510, 530, or 550 is reacted in a ring-openingpolymerization initiated by a base. Examples of bases that can be usedas initiators can include potassium hydroxide, sodium hydroxide, lithiumhydroxide, etc.

FIG. 6D is a chemical reaction diagram illustrating a process 600-4 offorming flame-retardant vanillin-based polymers 640 derived from themono-propylene-carbonate-functionalized vanillin-derived monomers 520,540, and 560, according to some embodiments of the present disclosure.In process 600-4, the mono-propylene-carbonate-functionalizedvanillin-derived monomer 520, 540, or 560 is reacted in a ring-openingpolymerization initiated by a base. Examples of bases that can be usedas initiators can include potassium hydroxide, sodium hydroxide, lithiumhydroxide, etc.

In addition to the polymers 610, 620, 630, and 640 illustrated in FIGS.6A-6D, the flame-retardant vanillin-derived monomers 108 disclosedherein can be used in the synthesis of other flame-retardant polymers.An array of classes of flame-retardant polymers can be made withdifferent combinations of monomers. These polymerization processes arein accordance with polymer chemistry platforms that can includepolyhydroxyurethanes, polycarbonates, polymers obtained by radicalpolymerization, polyurethanes, polyesters, polyacrylates,polycarbonates, epoxy resins, polyimides, polyureas, polyamides,poly(vinyl-esters), etc.

One example of an application of polymers made, at least in part, fromflame-retardant vanillin-derived monomers 108 is in plastics used inelectronics hardware. Additional applications can include acousticdampening, cushioning, plastics, synthetic fibers, insulation,adhesives, etc. The flame-retardant vanillin-derived monomers 108 canalso be used to make adhesives such as bio-adhesives, elastomers,thermoplastics, emulsions, thermosets, etc. Further, materialscontaining the flame-retardant vanillin-derived monomers 108 can beincorporated into various devices with electronic components that caninclude printed circuit boards (PCBs), semiconductors, transistors,optoelectronics, capacitors, resistors, etc.

Resins for printed circuit boards (PCBs) can be made flame-retardant byincorporating polymers that are made, at least in part, fromflame-retardant vanillin-derived monomers 108. PCBs are electricalcircuits that can be found in most types of electronic device, and theysupport and electronically connect electrical components in the device.PCBs are formed by etching a copper conductive layer laminated onto aninsulating substrate. The insulating substrate can be a laminatecomprising a resin and a fiber. Many resins in PCBs contain a polymer,such as an epoxy, a polyhydroxyurethane, a polyurethane, apolycarbonate, a polyester, a polyacrylate, a polyimide, a polyamide, apolyurea, a poly(vinyl-ester), etc. Using polymers that incorporate theflame-retardant vanillin-derived monomers 108 can prevent the PCB fromcatching fire when exposed to high temperature environments orelectrical power overloads.

It should be noted that, in some embodiments, the compounds describedherein can contain one or more chiral centers. These can include racemicmixtures, diastereomers, enantiomers, and mixtures containing one ormore stereoisomer. Further, the disclosed can encompass racemic forms ofthe compounds in addition to individual stereoisomers, as well asmixtures containing any of these.

The synthetic processes discussed herein and their accompanying drawingsare prophetic examples, and are not limiting; they can vary in reactionconditions, components, methods, etc. In addition, the reactionconditions can optionally be changed over the course of a process. Insome instances, reactions that involve multiple steps can be carried outsequentially, and, in other instances, they can be carried out in onepot. Further, in some embodiments, processes can be added or omittedwhile still remaining within the scope of the disclosure, as will beunderstood by a person of ordinary skill in the art.

What is claimed is:
 1. A flame-retardant vanillin-derived monomer with aformula of:

wherein M is a flame-retardant substituent; wherein FR is aphosphorus-based moiety; and wherein R is a substituent selected from agroup consisting of a phenyl substituent, an allyl substituent, anepoxide substituent, and a propylene carbonate substituent.
 2. Theflame-retardant vanillin-derived monomer of claim 1, wherein the M isselected from a group consisting of substituents with formulas of:

wherein FR is a second phosphorus-based moiety; and wherein R is asecond substituent selected from the group consisting of the phenylsubstituent, the allyl substituent, the epoxide substituent, and thepropylene carbonate substituent.
 3. The flame-retardant vanillin-derivedmonomer of claim 1, wherein the FR is a phosphoryl moiety with a formulaof:


4. The flame-retardant vanillin-derived monomer of claim 1, wherein theFR is a phosphonyl moiety with a formula of:


5. The flame-retardant vanillin-derived monomer of claim 1, wherein theflame-retardant vanillin-derived monomer has two functional groups thatparticipate in polymerization.
 6. The flame-retardant vanillin-derivedmonomer of claim 1, wherein the flame-retardant vanillin-derived monomerhas one functional group that participates in polymerization.